Oxocyclopenta(c)pyrroles

ABSTRACT

PROCESS FOR PREPARING 2 - AMINOLKYLPYRROL - 3 - YL KETONES AND DERIVATIVES THEREOF, AND OXOCYCLOPENTA(C)PYRROLES THUS PRODUCED. THE PROCESS IS CARRIED OUT BY QUATERNIZING 2-DIMETHYLAMINO- OR 2-PIPERIDINO-ALKYL-PYRROL-3-YL KETONES OR DERIVATIVES THEREOF, INCLUDING THOSE HAVING BI- AND TRICYCLIC NUCLEI, AND REACTING THE QUATERNARY SALTS EITHER WITH A BASE AND AN AMINE, OR, ALTERNATIVELY, WITH AN AMINE ONLY.

United States Patent Office 3,642,794 Patented Feb. 15, 1972 3,642,794 OXOCYCLOPENTA[c]PYRROLES Irwin J. Pachter, Woodbury, and Karl Schoen, Kew Gardens, N.Y., assignors to Endo Laboratories Inc., Garden City, N.Y.

No Drawing. Application Sept. 1, 1967, Ser. No. 664,942, which is a continuation-in-part of applications Ser. No. 575,303, Aug. 26, 1966, and Ser. No. 599,387, Dec. 6, 1966. Divided and this application July 15, 1968, Ser.

7 Int. Cl. C07d 27/54 U.s. C]. 2601-2475 B 4 Claims ABSTRACT OF THE DISCLOSURE Process for preparing 2 aminoalkylpyrrol 3 yl ketones and derivatives thereof, and oxocyc1openta[c]pyrroles thus produced. The process is carried out by quaternizing Z-dimethylaminoor 2-piperidino-alkyl-pyrrol-3-yl'ketones or derivatives thereof, including those havingbiand tricyclic nuclei, and reacting the quaternary salts either with a base and an amine, or, alternatively, with an amine only.

CROSS REFERENCE TO OTHER APPLICATIONS This application is a division of application Ser. No. 664,942, filed Sept. '1, 1967 and now abandoned, which application was-in turn a continuation-in-part of our copending applications Ser. No. 575,303, filed Aug. 26, 1966 and now abandoned, and Ser. No. 599,387, filed Dec. 6, 1966 and now abandoned. Certain of the compounds disclosedherein are described in our copending applications Ser. No. 403,387, filed Aug. 12, 1964 and now Pat. No. 3,410,857 issued Nov. 12, 1968, and Ser. No. 357,284, filed Apr. 3,1964 and now abandoned.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to novel compounds which are useful as tranquilizers, anti-depressants and analgetics.

(2) Description of the prior art Various compounds. within the following class are known and have been described, for example, in our above-noted copending applications.

in the "above formula:

halo-phenyl, (lower alkoxy)-phenyl, thienyl, furyl, or benzyl;

R and R may be linked to constitute an alicyclic ring having a maximum of 8 carbon atoms;

R designates hydrogen, alkyl, alkenyl or cycloalkyl, all having a maximum of 8 carbon atoms, phenyl or benzyl; and

R or R may be linked with R to constitute alicyclic rings having a maximum of 8 carbon atoms, those rings formed by linking R and R optionally being substituted by alkyl groups having 1-4 carbon atoms and those rings formed by linking R and R optionally being substituted by an alkyl or alkylidene group having l-4 carbon atoms, a benzylidene or a benzyl group.

X and Y are each the same or different and are hydrogen, lower alkyl, lower alkynyl, lower alkenyl, cycloalkyl, bicycloalkyl, hydroxy-lower alkyl, alkoxy-lower alkyl, lower dialkylamino, lower acyloxyalkyl, carbamoyloxylower alkyl, phenyl-lower alkyl, heteroaromatic-lower alkyl, heteroaryl and saturated heteroaryl, and wherein X and Y may be linked, and when linked constitute a heterocyclic ring of not more than eight members.

Some of the compounds embraced within the scope of general formula A, as set forth above, have heretofore been prepared, or may be prepared, through the Mannich reaction of the corresponding pyrrol-3-yl ketone with formaldehyde or a formaldehyde-yielding substance, e.g., paraformaldehyde, and a base XNH-Y as set forth in the following reaction scheme:

REACTION SCHEME I NH-H or with dimethylamine hydrochloride proceed most rapidly,

with better yield and with higher purity. However, it has not been possible to produce primary or secondary amino alkyl ketones by the method of Reaction Scheme I, that is to say, compounds of general formula A herein wherein the moieties X and Y may either or both be hydrogen.

Compounds where X and/ or Y are lower alkynyl, lower alkenyl, bicycloalkyl, alkoxy-lower alkyl, lower dialkylamino, heteroaromatic lower alkyl, heteroaryl and satuurated heteroaryl have not been disclosed heretofore.

SUMMARY OF THE INVENTION 3 FORMULA B Formula A REACTION SCHEME II In accordance with such process, which is the subject of our copending application Ser. No. 768,569, filed July 16, 1968, the dimethylamine Mannich base is quaterized with an alkyl halide or sulfate, suitably a lower alkyl halide or sulfate such as methyl-, ethylor propyl-bromide, chloride, iodide, or sulfate, and the resulting quaternary salt is treated with aqueous alkali, suitably aqueous sodium or potassium hydroxide, to produce the stable methylene derivative.

Upon interaction of the methylene compound with a new base there is produced a final product of good quality and in high yield.

The success of such process is a consequence of the unusual stability of the methylene compounds of the Formula B (in which the symbols R to R have the same meaning as in Formula A). The compounds of Formula B are more resistant to polymer-forming side reactions than are structurally comparable aryl derivatives such as the acrylophenones.

The novel compounds of present invention are those of Formula A wherein the moiety X and/or Y are hydrogen, which could not be satisfactorily prepared by the method of Reaction Scheme I. The present invention further includes compounds wherein X and/or Y are lower alkynyl, lower alkenyl, cycloalkyl, alkoxy-lower alkyl, lower dialkylamino, heteroaromatic lower alkyl, heteroaryl and saturated heteroaryl.

4 More particularly, the novel compounds within the scope of the present invention are those of the formula:

I (CH2):- R4

wherein n is 0; R R and R are hydrogen, alkyl having a maximum of 6 carbon atoms, phenyl, phenyl alkyl, the alkyl group of which has a maximum of 3 carbon atoms, substituted phenyl or substituted phenyl alkyl, in which the phenyl moieties may be substituted by halogen, alkyl of not more than 4 carbon atoms, or alkoxy of not more than 4 carbon atoms;

X and Y are each the same or different and are hydrogen, lower alkyl, lower alkynyl, lower alkenyl, cycloalkyl, hydroxy lower alkyl, lower alkoxy-lower alkyl, di

(lower alkyl) amino, lower alkanoyloxy lower alkyl,

carbamoyloxy-lower alkyl, phenyl-lower alkyl, heterocyclic radicals, heterocyclo lower alkyl radicals or, together with the nitrogen atom to which they are attached, a single heterocyclic unit.

The compounds of the foregoing formula have central nervous system activity; and are particularly useful as tranquilizers, ataractics,and sedatives. They are also useful as analgetics and antidepressants.

The compounds can be put up in customary pharmaceutical composition forms such as tablets, capsules, syrups, suppositories etc., in accordane with the techniques of pharmaceutical compounding employing appropriate carrier or vehicular materials asexcipients, etc.

The compounds may be administered as dosage levels of about 0.07-3 mg./kg., preferably between 0.71.8 mg./ kg. daily. A compound prepared by the process described herein showed marked antipsychotic activity in humans 'when administered at the preferred leveli.e., -125 PREFERRED EMBODIMENTS OF THE INVENTION In the preferred embodiments of the present invention, R is hydrogen; a lower alkyl group, such as methyl, ethyl, propyl, butyl or hexyl; phenyl; phenyl lower alkyl, such as benzyl, phenethyl or phenylbutyl; or substituted phenyl or substituted phenylalkyl, wherein the substituent on the phenyl ring is chloro, bromo, or fiuoro, alkyl of not more than 4 carbon atoms, or alkoxy of not more than 4 carbon atoms, i.e., methoxy, ethoxy, propoxy or butoxy.

Concurrently, R and R may be lower alkyl groups, such as methyl, ethyl, propyl, butyl or hexyl; phenyl; phenyl lower alkyl, such as benzyl, phenethyl or phenylbutyl; or substituted phenyl or substituted phenyl alkyl, wherein the substituent on each phenyl ring is chloro,

bromo, or fiuoro, alkyl of not more than 4 carbon atoms,

or alkoxy of not more than 4 carbon atoms, i.e., methoxy, ethoxy, propoxy or butoxy.

X and Y are the same or different and may each be hydrogen; lower alkyl, such as methyl, ethyl, butyl, pentyl, hexyl, or heptyl; lower alkynyl, such as propynyl, butynyl or pentynyl; lower alkenyl, such as propenyl, butenyl or hexenyl; eycloalkyl, suitably cyclo-lower alkyl, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cyclooctyl; hydroxy lower alkyl; lower alkoxy lower alkyl, di (lower alkyl) amino, such as 'dimethylaminoj lower acyloxy alkyl, suitably lower alkanoyloxy lower alkyl; carbamoyloxy lower alkyl; phenyl lower alkyl; a heterocyclic radical or a heterocyclo lower alkyl radical.

When either X or Y is a heterocyclic radical or a heterocyclo lower alkyl radical, the heterocycle may be a piperidino, piperidinyl, pyrrolidinyl, morpholino, morpholinyl, thiomorpholino,. thiornorpholinyl, piperazinyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazolyl quinolyl, isoquinolyl, pyrrolyl, thienyl, furyl, oxazolyl or tetrazolyl group.

Alternatively, X and Y may, together with the nitrogen atom to which they are attached, form a heterocyclic unit. In such instance they may jointly define a heterocycle selected from the groupconsisting of piperidino, (lower alkyl piperidino, di(lower alkyl) piperidino, (lower alkoxy) piperidino, hydroxypiperidino, alkoxycarbonylpiperidino, phenyl hydroxypiperidino, (lower alkanoyl) piperidino, pyrrolidinyl, (lower alkyl) pyrrolidinyl, (lower alkoxy) pyrrolidinyl, hydroxy-pyrrolidinyl, morpholino, (lower alkyl) morpholino, thiomorpholino, (lower alkyl) thiomorpholino,piperazinyl, (lower alkyl) piperazinyl,di(lower alkyl) piperazinyl, (lower alkoxy) piperazinyl, phenylpiperazinyl, chlorophenylpiperazinyl, tolylperazinyl, (methoxyphenyl) piperazinyl, hydroxyalkylpiperazinyl, lower alkanoyloxy-lower alkyl-piperazinyl, carbarnoyloxy-lower alkyl piperazinyl, and azabicyclolower alkyl, wherein lower alkanoyl, lower alkyl and lower alkoxy have 1-5 carbon atoms.

In a preferred modification of the process for synthesizing the oxo-cyclopenta[c]pyrroles hereof, a dimethylamino Mannich base within general Formula A is utilized as the start.

Although dimethylamino Mannich bases are most advantageous. as starting materials for this process, other lower alkylamino Mannich bases as well as heterocyclicbases such, asthe piperidino Mannich base may also be used.

In the preferred procedure, the Mannich base, which is usually obtained in the form of" an acid salt, suitably the hydrochloride, is treated with aqueous ammonia and the free Mannich base isolated from the aqueous mixture. In a suitable mode of isolation, the base is extracted from the reaction mixturewith a low boiling, reaction inert, water-immiscible solvent, such as ethyl acetate, diethyl ether, or the like. Upon evaporation of the solvent, the base 'is taken up in a suitable organic solvent, preferably a non-hydroxylic, polar organic solvent such as acetone, and treated with the quaternizingagent. In the preferred modification, gaseous methyl bromide is used as the quaternizing agent, and is bubbled into the solution of the Mannich base until no further separation of the quaternary is noted. The quaternary salt is then isolated as a residue by filtration, and recrystallized, suitably from a lower alkanol such as methanol.

The quaternary salt has the general Formula C where R R R R and R are as above.

R R and R are alkyl having from 1 to 8 carbon atoms;

however, R and R may be joined to form a ring containing up to 7 carbon atoms, i.e., the piperidine, pyrrolidine and hexarnethylenimine" nuclei;

Z is an inorganic radical such as chloride, bromide, sulfate, or the like.

The quaternary salt of the Mannich base, for example, the methobromide, the methiodide, the methos ulfate, or the like, is dissolved in water and treated with an excess of an alkali such as aqueous sodium hydroxide, ammonia, or 'a strong organic base such as triethylamine. The desired vinyl compound of general'Formula B separates as aprecipitate, and is isolated. The vinyl compound of general Formula B is then purified, preferably by recrystallization from the suitable solvents such as a lower alkanol, preferably ethanol.

The vinyl compounds of general Formula B are then reacted with amines of the general formula X-NH-Y, wherein X and Y have the significance set forth hereinabove, and may thus represent primary amines or sec ondary cyclic or acrylic amines.

The reaction of the amine with the compound of Formula B may be carried out in a number of modifications. The preferred mode will depend upon the reactivity and volatility of the respective reactants. Many primary and secondary amines will react with compounds of Formula B at ambient temperature, that is to say, from about 10 C. to about 30 C. with evolution of heat where the reaction is carried out in a solvent such as a lower alkanol, for example, methanol, ethanol, propanol, butanol, and the like, or in di-lower alkyl ketones, for example, acetone, methylethyl ketone, di-isopropyl ketone, and the like, as Well as in lower alkyl lower alkanoates such as ethyl acetate, propyl acetate and butyl propionate.

Where desired, the reaction may be carried out in similar solvents under reflux at temperatures of from about 50 to about C. Where it is desired to use low boiling solvents, particularly with volatile amines, the reaction may be advantageously carried out in pressure ves sels at temperatures up to about 150 C. In yet another modification of the procedure, it is sometimes advantageous to use excess of the amine base itself as the solvent.

Reaction time varies from one minute to 24 hours, depending upon the nature of the reactants. Most reactions proceed to completion in less than 8 hours.

Among the amines which may be employed in the process of the present invention which may be primary or secondary, may be included those bearing alkyl groups, suitably lower-alkyl groups, such as methyl, ethyl, propyl, and butyl; cycloalkyl groups, such as cyclopropyl and cyclohexyl; alkenyl groups, suitably loweralkenyl groups, such as allyl, methallyl and hexenyl; alkynyl groups, suitably lower alkynyl groups, such as propynyl, butynyl, and hexynyl groups; or phenyl-alkyl groups, suitably phenyl lower alkyl groups such as benzyl, phenethyl, and phenylbutyl groups; alkoxy-alkyl groups, suitably lower alkoxylower alkoyl groups, such as methoxyethyl, ethoxyethyl, butoxyethyl, pentoxypropyl; hydroxyalkyl groups, suitably hydroxy-lower alkyl groups, such as hydroxyethyl, hydroxypropyl, hydroxybutyl, or hydroxyhexyl, dialkylamino, such as dimethylamino.

Also included within the scope of the amines used in this process are heterocyclic secondary amines, wherein the secondary amino function is part of the cyclic moiety which may, if desired, itself be substituted. Preferred among these compounds are five or six membered heterocyclic amines containing at least one nitrogen-atom in the ring, and from zero to two other heteroatoms of the group oxygen, nitrogen and sulfur such as piperidino, (lower alkyl) piperidino, di(lower alkyl) piperidino, (lower alkoxy) piperidino, hydroxypiperidino, alkoxycarbonylphenylpiperidino, phenylhydroxypiperidino, (lower alkanoyl) piperidino, pyrrolidinyl, (lower alkyl) pyrrolidinyl, (lower alkoxy) pyrrolidinyl, hydroxypyrrolidinyl, morpholino, (lower alkyl) morpholino, thiomorpholino (lower alkyl) thiomorpholino, di-(lower alkyl) thiomorpholino, (lower alkoxy) thiomorpholino, piperazinyl, (lower alkyl) piperazinyl, di-lower alkyl) piperazinyl, (lower alkoxy) piperazinyl, phenylpiperazinyl, chlorophenylpiperazinyl, tolylpiperazinyl, (methoxyphenyl( piperazinyl, hydroxyalkylpiperazinyl, lower alkanoyloxy lower alkylpiperazinyl, carbamoyloxy-lower alkyl piperazinyl and azabicycloalkyl such as 3-azaspiro[5,5]undecany] and 3-azabicyclo[3,2,2]nonyl. The terms lower alkyl and lower alkoxy refer to both straight and branched chain radicals of no more than 5 carbon atoms.

Furthermore, there are included primary and secondary amines wherein one of the substituents of the amino moiety corresponds to .a radical derived from any of the aforementioned heterocyclic groups, for example, morpholinyl, pyrrolidinyl, thiomorpholiny], piperazinyl, as well as the unsaturated derivatives thereof, for example, picolyl, tetrazolyl, piperazinyl, and the like.

In another modification of the process, the quaternary salt (Formula C) derived from the starting material Mannich base of Formula A may be converted into the desired end product without the isolation of the intermediate methylene compound of Formula B. In this modification as set forth in Reaction Scheme II, the new organic base, that is to say, the amine, may serve as both the source of alkali and as the reactant.

The novel dimethylaminoalkyloxoisoindoles of this invention are readily prepared by the process of Reaction Scheme I, starting with an oxoisoindole.

Other aminoalkyloxoisoindoles are most satisfactorily derived from the corresponding dimethylaminoalkyloxoisoindole by the general method of Reaction Scheme II, although many products which are tertiary amines may also be prepared by the process of Reaction Scheme I.

The following examples describe preferred embodiments of the novel oxo-cyclopenta[c]pyrroles of this invention.

The temperatures in the following examples are in degrees Centigrade.

EXAMPLE 1 2,4,5 ,6-tetrahydro-l ,3-dimethyl- -dimethylaminomethyl- 4-oxocyclopenta [c] pyrrole A mixture of 30.8 g. of diethyl 2,5-dimethyl-3-pyrrolyl methylmalonate, 19 g. of 85% potassium hydroxide and 17 ml. of water was heated on a steam bath under nitrogen for one hour. The resulting solution was acidified to congo red paper with 6 N hydrochloric acid. The liberated acid was extracted with ether, dried over magnesium sulfate and distilled to elfect decarboxylation. The 2,5-dimethylpyrrole-3-propionic acid boiled at l53l54/0.7 0.8 mm.

The acid was mixed with five times its weight of polyphosphoric acid and heated at 135 for one hour. The mixture was then poured into water. The solid was collected and purified by dissolving it in benzene and passing the benzene solution through a short column of alumina. 2,4, 5,6-tetrahydro-1,3-dimethyl4-oxocyclopenta [c] pyrrole crystallized from benzene, M.P. 245-248 (decomposition).

A mixture of 7.0 g. of 2,4,5,6-tetrahydro-1,3-dimethyl- 4-oxocyclopenta [c] pyrrole, 5.2 g. of dimethylamine hydrochloride, 1.6 g. of paraformaldehyde and 50 ml. of ethanol was heated under reflux for 5 hours. An additional gram of paraformaldehyde was added and the reaction continued for a further 5 hours. The ethanolic solution was concentrated and cooled. The product crystallized and was purified by recrystallization from ethanol.

EXAMPLE 2 2,4,5,6-tetrahydro-l,3-dimethyl-5-morpholinomethyl- 4-oxocyclopenta [c] pyrrole hydrochloride A g. portion of 2,4,5,6-tetrahydro-1,3-dimethyl-5- methylene-4oxocyclopenta [c] pyrrole, 10 ml. of morpholine and 50 ml. of ethanol were heated under reflux for 24 hours. Evaporation of the solvent and dilution with water yielded the product 2,4,5,6-tetrahydro-1,3-dimethyl- 5-morpholinomethyl-4-oxocyclopenta [c] pyrrole. It was converted into the crystalline hydrochloride salt.

The active compounds of this invention may be taken in tablets or capsules in doses of 1-100 mg., in syrup at 0.5- mg/ml. concentration, in 1-50 mg. suppositories or by parenteral injection in 05-50 mg./ml. concentration. More particularly, the oxocyclopenta [c] pyrroles hereof may be formulated in the same manner as the oxoisoindoles identified in the following examples.

8 EXAMPLE 3 Ingredients: Mg./ tablet 4,5 ,6,7-tetrahydro-l,3-dimethyl-S-dimethylaminoethyl-4-oxoisoindole hydrochloride 10 Lactose USP (spray dried) 170 Starch USP 10 Magnesium stearate USP 1 Flavor, q.s.

All above ingredients were passed through a 60-mesh sieve, blended for 30 minutes and compressed directly into tablets on a suitable tablet press at a weight of 191 mg., using a A biconcave scored punch.

EXAMPLE 4 7 Ingredients: Mg./suppository 4,5,6,7-tetrahydro-1,3-dimethyl-5 morpholinomethyl-4-oxoisoindole hydrochloride Cocoa butter qs The drug and cocoa butterare combined, mixed thoroughly and formed into 2 grain suppositories.

EXAMPLE 5 Ingredients: Mg./capsule 4,5,6,7-tetrahydro-1,3-dimethyl-4-oxo 5 piper idinomethylisoindole hydrochloride Lactose USP 100 Magnesium stearate 1 Amorphous silicon dioxide (Cab-O-Sil) 5 These ingredients were combined, blended and passed through a No. 1 screen of Fitzpatrick comminutor machine before encapsulating into a.two-piece hard gelatin No. 3 capsule on a standard capsulating machine at a net weight of 126 mg.

EXAMPLE 6 Ingredients: Mg./ml. 4,5,6,7-tetrahydro-1,2,3-trimethyl 5 dimethylaminomethyl-4-oxoisoindole hydrochloride 5 Sodium chloride (for isotonicity) q.s. Methylparaben USP 1.8 Propylparaben USP 0.2 Water q.s.

The above ingredients are combined in sterile solution for parenteral use.

and made up to a volume of one liter.

We claim: 1. A compound of the formula:

wherein n is 0;

R R and R are hydrogen, alkyl having a maximum of 6 carbon atoms, and phenyl;

X and Y are the same or dilferent and are hydrogen,

lower alkyl, lower alkynyl, cycloalkyl, heterocyclolower alkyl in which the heterocycle is a piperidino, piperidinyl, morpholino, or morpholinyl, group or, together with the nitrogen atom to which they are attached X and Y define a heterocycle selected from the group consisting of piperidino, pyrrolidinyl, morpholino, thiomorpholino, and phenylpiperazinyl; or

the pharmaceutically acceptable acid addition salts thereof. 2. A compound according to claim 1, wherein R is hydrogen or lower alkyl and R and R are lower alkyl. 3. A compound according to claim 1 having the designation 2,4,5,'6-tetrahydro-1,3-dimethyl-5 dimethylaminomethy1-4-oxo-cyclopenta[c]pyrrole, and the acid salts 10 thereof.

4. A compound according to claim 1 having the designation 2,4,5,6-tetrahydro 1,3 dimethyl 5 morpholinomethyl-4-oxopenta[c]pyrrole hydrochloride, and the acid salts thereof.

References Cited UNITED STATES PATENTS 3,491,093 1/1970 Pachter et al 260-2475 ALEX MAZEL, Primary Examiner J. A. NARCAVAGE, Assistant Examiner 

